The Ngunnhu traps on the Barwon river were once a great gathering site for Indigenous people, but their present custodians say damage and neglect since white settlement is a shameful blot on Australia’s heritage record.

The people of Brewarrina proudly call their fish traps “the oldest manmade structure in the world.

Located in north-west New South Wales, the traps lie where the Barwon river makes a curve near the largely Aboriginal town of Brewarrina.

When the water level is low, bulrushes grow tall as waist-high and the sun bears down on exposed rocks – ordinary rocks, arranged in an unusual way.

The rocks surround 12 teardrop-shaped pools across half a kilometre. In the past, fish were herded in through small openings that the locals would quickly close shut with a few rocks. The pen walls are at different heights, allowing them to be used at different water levels, and have proved resistant to damage in the face of high and fast water flows.

When the fish traps were added to Australia’s national heritage list in 2005, they were described as “the largest traps recorded, showcasing a thorough understanding of “dry stone wall construction techniques, river hydrology and fish ecology. Due to their size, design and complexity they were considered “exceptionally rare.

Quite how old these structures are is unclear. Dr Duncan Wright, an archaeologist at Australian National University, says although there has been no reliable radiocarbon dating, archaeological data suggests the traps are more recent than local claims that they are 40,000 years old . “To my knowledge there have been no fish traps found that date back that far, certainly none in Australia, he says.

Other traps in NSW appear to date to within the past 3,000 years, with the majority less than 1,000 years old, he says. “This suggests a widespread phenomenon involving stone-lined fish traps. Brewarrina is likely to be a part of this, however, without an exact age for the site it remains possible that it could be older.

Even if the traps are “only 1,000 years old, it doesn’t detract from their importance, says Wright. They remain a “remarkable example of Aboriginal innovation, an ability to understand and exploit the natural landscape and form one part of a growing body of work that challenges how hunter-gatherer Australian societies have long been perceived.

“Fish traps became prominent across Australia – from the Torres Strait islands to south-east Australia – during the past few thousand years, suggesting interconnections across tens of thousands of miles. Life in pre-European Australia was a hell of a lot more complex than we might think, he says.

These traps, called Ngunnhu by the local Ngemba people, have strong spiritual connections to an ancestral being called Baiame, who legend says threw his net across the Barwon, thereby creating their design. Along with his sons Boomaooma-nowi and Ghinda-inda-mui, he is said to have built the traps using dug up stones and boulders.

According to the story, Baiame then allocated the traps to different family groups, making them responsible for their use and maintenance. The area became a meeting place for 20-odd nations, including the Morowari, Paarkinji, Weilwan, Barabinja, Ualarai and Kamilaroi people, who would gather each year in a kind of parliamentary meeting.

It was an ideal location: teeming with enough freshwater mussels, emu and crayfish to feed all the elders, men, women and children. They gathered from across the northern basin for corroborees, initiation ceremonies and trade meetings.

Ngemba man Feli McHughes says the ingenuity of the traps lay in how they did not disrupt the flow of the river. “It could be left there permanently – when the gate wasn’t closed the fish could come back out if they wanted.

But he says things changed when the “white man came here and traditional practices began to “go underground. The Ngemba people were rounded up and ordered to live at Brewarrina Mission, nine miles away. “And they weren’t allowed to come here and get fish from these traps, McHughes says.

Stones were removed by European settlers in the 1860s and 1920s for construction work. And the traps suffered a further blow in the 1960s, when a weir was installed just a few metres upstream. A report for the NSW Healthy Rivers Commission subsequently found it was “unnecessary for a secure town water supply and that “reconciliation and justice suggested it should be removed. The concrete slab halts the river’s natural water flow and at times the traps run dry.

Between 1986 and 2009, $64,000 in NSW heritage grants was approved for conservation of the traps. A local community group, the Brewarrina Business Centre Cooperative, is responsible for their condition. Its museum runs daily tours of the traps, charging $10 per person, and in 2014 had about 1,000 visitors.

Cooperative member Bradley Hardy agrees the weir has wreaked havoc on the river and the traps. “If the water was up more we wouldn’t have so much trouble with the bulrushes. The water would wash the mess away from the traps. And native fish – which swim upstream – wouldn’t struggle so much in the face of an aggressive population of European carp that has overrun the river system.

Hardy and his colleagues work diligently in their spare time to clean out rubbish and clear away the bulrushes. His vision for the place is modest: “If we can get about two or three more labourers in the area that’ll be real good.

He says the mood of the town is deeply connected to the state of the river flow. “We’re river people. When the water is running again it creates a good vibe.

The neglected state of the traps speaks to a broader issue plaguing Aboriginal cultural heritage in NSW. Since 1969, objects of Aboriginal cultural significance have fallen under the National Parks and Wildlife Act, but continued to be undervalued and poorly protected, with limited support given to traditional owners. Recognising the many instances where this system has failed, in 2011 the state government kicked off a process of reform with the last phase of community consultation in review by the office of environment and heritage.

NSW is covered in important cultural sites and objects, including bora rings, burial carved trees, hand-crafted coolamons and thousand-year-old rock artwork – but only 100 have been officially declared in the state (and come under the Act’s protection) since 1974. NSW Aboriginal Land Council chairman Craig Cromelin says the rest are hidden from non-Aboriginal people and will remain so until legislation is “made solid and strong.

McHughes hopes for more tourism investment, but is sceptical about the chances. Welfare dependence is “sterilising the spirit of the Aboriginal people, he says, and heritage conservation represents an opportunity to create more culturally appropriate work – of which there is little in a town with a 13% unemployment rate.

And while Australian academics are finally acknowledging the scientific and engineering ingenuity evidenced by Aboriginal heritage sites such as the traps, McHughes is rapidly giving up on hope mainstream Australia will likewise recognise its value, believing them to be “embarrassed by it in context of the historical debasement of his people.

He says the national heritage “couldn’t give two hoots about its condition. “It’s the oldest manmade structure in Australia. To see the dilapidated state they’re in – it’s a disgrace to the nation. Would someone just let the Opera House go like that? And how much more important are the traps to the heritage of this country?

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